Question

I can ferment glucose and can grow in anaerobic environment via fermentation of this sugar. I also produce purple color in a microbiological test to which oil is added to stimulate the formation of anaerobic environment.

1. What is the substrate of the enzyme, the presence or absence of which will determine whether the test, with the purple color, will be positive or negative

a) glucose            b) amino acid(s)               c) protein                      d) lipids

2. What is the indicator of the test media from question 13.

a) amylase    b) methyl green    c) ferric ammonium citrate    d) bromcresol purple     e) iron

3. What is the nature of the chemical reaction catalyzed by this enzyme?

a) hydrolysis of nucleotides                                   b) hydrolysis of proteins

c) decarboxylation of amino acids                        d) deamination of amino acids

I can not grow in a viscous environment. I don’t have DNAse.

4. What will be the color of the growth around me, if I lack these skills?

a) colorless       b) green              c) red                      d) black

5. I can remove amine groups from amino acids such as phenylalanine. What will be the color associated with my growth after the addition of the appropriate indicator?

a) colorless                b) green               c) red                           d) black

6. I am a test where no indicator is needed. I am whitish in color to begin with and when bacteria that grows on me makes the right enzyme, you could see a halo around its growth. What is my name?

a) lipase test                 b) Glucoronate test                 c) amylase test                         d) casease test

Answer 1

Amino acid is the substrate of the enzyme, the presence or absence of which will determine whether the test, with the purple color, will be positive or negative.

Bromcresol purple is the indicator of the test media as Bromocresol purple is a pH indicator which changes color from yellow (at low pH 5.2) to violet (above pH 6.8). It is mainly used as a fluorescent stain in yeast cells.

decarboxylation of amino acids is the nature of the chemical reaction catalyzed by this enzyme.The decarboxylase test needs to be anaerobic so to overlay the broths with a layer of sterile mineral oil.

microbe that grow in a viscous environment and don’t have DNAse will be colorless. as  DNase are extracellular endonucleases that cleave DNA and release free nucleotides and phosphate

Green color associated with my growth after the addition of the appropriate indicator after  removing amine groups from amino acids such as phenylalanine.as Phenylalanine deaminase medium tests the ability of an organism to produce the enzyme deaminase. This enzyme removes the amine group from the amino acid phenylalanine and releases the amine group as free ammonia. As a result of this reaction, phenylpyruvic acid is also produced. Phenylalanine agar, also known as phenylalanine deaminase medium, contains nutrients and DL-phenylalanine. It is used to differentiate members of the genera Proteus, Morganella and Providencia from other Enterobacteriaceae. After incubation, 10% ferric chloride is added to the media; if phenylpyruvic acid was produced, it will react with the ferric chloride and turn dark green. If the medium remains a straw color, the organism is negative for phenylalanine deaminase production.

casease test is the test where no indicator is needed as Skim milk agar is a differential medium that tests the ability of an organism to produce an exoenzyme, called casease, that hydrolyzes casein. Casein forms an opaque suspension in milk that makes the milk appear white. Casease allows the organisms that produce it to break down casein into smaller polypeptides, peptides, and amino acids that can cross the cell membrane and be utilized by the organism. When casein is broken down into these component molecules, it is no longer white. If an organism can break down casein, a clear halo will appear around the areas where the organism has grown.